In the evening of February the 6th, Paul McCartney decided that he needed saxes for “Lady Madonna”. Phone calls were made immediately to find four sax players. Soon Harry Klein (baritone sax), Bill Jackman (baritone sax), Ronnie Scott (tenor sax) and Bill Povey (tenor sax) arrived at Abbey Road studios in London. According to Harry Klein there was no written music. They invented some riffs, wrote down a few notes, then they had to record their part 101 times. These musicians are all jazz musicians. It was typical for pop and rock recordings in the sixties to call in well trained jazz musicians, because they could invent interesting lines on the spot and were absolutely in command of their instruments. Ronnie Scott (1927-1996) is the co-founder of the famous Ronnie Scott’s Jazz Club in London, by the way.
Source: Mark Lewisohn, “The Complete Beatles Recording Sessions”, 1988, page 133